Overrunning clutches of the type that have a complement of spring engergized cylindrical rollers are found in many applications where it is desired to allow relative rotation in one direction only between a race with a cylindrical pathway, and a coaxial cam race with a series of sloped cam ramps that confront the pathway. The typical roller clutch has a cage that provides its basic structural framework and which also provides roller retention pockets that axially confine the rollers, as well as providing a mounting foundation for the roller energizing springs. The total unit of cage, rollers and springs is installed in one step between the races, typically by a method known as ringing in. Ringing in involves sliding the clutch onto the cam race and then pushing the pathway race axially into place with a simultaneous twisting motion. The twisting of the pathway race shifts the rollers down their respective cam ramps from a shipping position to an operative position, compressing the springs. After installation, each roller is then continually spring biased up its respective cam ramp into engagement between the pathway and cam ramp, where it is ready to lock up quickly. In many such applications, because of running eccentricity between the clutch races, it is necessary that the rollers move circumferentially over a significant distance, traveling continually up and down the cam ramp so as to always be in the optimal lock up ready position. This motion of the rollers is generally referred to as the roller travel, and it can cover a distance of more than a roller diameter, as well as being quite rapid at high race speeds.
The roller energizing spring should do nothing, in the ideal case, to limit roller travel, which would jeopardize efficient clutch operation. The spring should, therefore, be able to freely flex over a sufficient distance to follow the roller. It is also important that the spring not cause the roller to axially skew, and, ideally, the spring would actually help maintain the roller stable and parallel to the race axis during roller travel. While cages are commonly molded of plastic in one piece, often by the economical by pass molding technique, the most common roller energizing spring is still a separate metal piece. Such springs are generally fixed to the cage by some type of locking latch, and the separate and individual assembly of each spring to the cage is one of the most difficult, time consuming and expensive aspects of roller clutch manufacture.
It is known in the art to avoid separate spring assembly by integrally molding the cage and energizing springs. Such units, however, have generally found use only in very lightly loaded, low force applications, because they do not provide for significant, unimpeded roller travel. One such design is disclosed in U.S. Pat. No. 3,260,333 to Benson et al, which has generally V shaped springs integrally molded to the cage cross bars, although the cage is not of a configuration that can be by pass molded. As the roller travels, the V opens and closes. The degree of spring flexing is deliberately limited, however, so the possible roller travel is not very large. A more detailed analysis of this particular spring will be given below. Another integrally molded cage-spring unit is disclosed in U.S. Pat. No. 4,620,806, in which the spring is an integrally molded flap that initially sticks radially outwardly beyond the OD of the annular space between the races, but which is bent inwardly and down at installation. The flaps then each push out out against a roller to bias it. This design has the advantage of being by pass moldable, but there is, again, a very limited roller travel. As can be seen in FIG. 1, which shows the roller shipping position, if the roller were to shifted at all during clutch installation, there would be almost no flex room left at all for the spring, and, consequently, very little roller travel. In addition, the flap would likely be deformed radially outwardly into one of the races as it flexed if the roller did have a significant travel distance. Furthermore, a flap of the type shown would block the possibility of any significant radial lubricant flow across the annular space between the clutch races, making it unsuitable for use in many automatic transmission environments.